JPH01197868A - Logical simulation method - Google Patents

Abstract

PURPOSE:To execute a logical simulation of high efficiency which does not execute an unnecessary processing by propagating a signal to an input side from an output side of a circuit which becomes an object of the logical simulation, checking from the input side whether this signal is being propagated or not and re-forming a component for exerting no influence on an external output of the circuit. CONSTITUTION:An arbitrary signal is propagated to an input side from an output side of a circuit which has been stored on a memory of a computer as an object of a logical simulation. Subsequently, whether this signal is being propagated to a component or not to the output side from the input side is checked, and by removing the component to which the signal is not propagated, a circuit which does not contain the component having no output is re-formed. In such a way, a logical simulation of high efficiency in which an unnecessary processing is not executed can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for stain reversing logic circuits.

The conventional technology logic V mini-sheet 1 inputs a circuit description of a logic circuit and a time-varying signal value obtained from an external input preview of this circuit, and calculates the time-varying signal value appearing at the output of a component in the circuit. It is a software imitation of change.

During the execution of the logic simulation process, the signal value appearing at the output of the component is determined based on the function of the component and the signal value of the input of the component, and the signal value of the output thus determined is The signal becomes an input to the next-stage component, and processing is performed to sequentially determine the signal value of the output of the component in this circuit.

Problems to be Solved by the Invention However, in the conventional method, it is necessary to use a component element that does not have an output, in which a signal is input, but the signal value output as an output must be propagated to P:ζ. If there is a component in the circuit (for example, an unused product term line of ψ-LA) that causes the incoming signal to stop because there is no Regarding the constituent elements, as with other constituent elements that have an output to the next stage, unnecessary processing is performed on constituent elements that do not have an output, such as determining the signal value of the output.

Akira Honshizuku - In view of the above points, it is to provide a logic simulation method for avoiding unnecessary processing for the component without an output, which is performed during the execution of the logic iV gate renewal, within this month. do.
.

Means for Solving the Problems In order to solve the above problems, the present invention propagates a signal from the output side to the input side of a circuit stored in the memory of a computer as an object of logic simulation, and transmits the signal from the input side. This is a logic simulation method that removes the above-mentioned constituent elements and executes logic simulation by checking the presence or absence of propagation.

Function The present invention has 1. An arbitrary signal is propagated from the output side to the input side of the circuit stored in the computer's memory as the target of logic simulation, and then whether this signal is propagated from the input side to the output side to the constituent elements. Efficient logic simulation that eliminates unnecessary processing by re-forming a circuit that does not include components with no output by examining the / Enables

Example Hereinafter, the present invention will be further illustrated based on the drawings.

Explain in detail.

FIG. 1 is a flowchart illustrating the flow of processing performed to reconfigure a circuit that does not include a component without an output, which is an essential part of the present invention.

The processing shown in the flowchart of FIG. 1 will be specifically explained using the circuit shown in FIG.

'In Figure 1, first, a process is performed to select the component corresponding to the external output of the circuit stored in the memory of the computer as the target of the logic simulation (hereinafter referred to as the circuit to be the target of the logic simulation). (Step 11). Here, a component corresponding to an external output is one whose output value can be observed from outside the circuit.

In the circuit of Fig. 2, external output 211 and external output 21
2 is selected.

Next, in FIG. 1, an arbitrary signal is propagated to the selected component to indicate that the component influences the value of the external output of the circuit (step 12).

Now, assuming that a signal value of 1 is propagated, the external output 211 and the external output 21.2 in FIG. 2 each have a signal value of 1.
will have. - In FIG. 1, the process of adding the component connected to the input of the component to which the signal value propagated in step 12 into the next candidates for signal value propagation (
There is step 13), but in FIG. This is the next candidate for value propagation.

・ ・ Next, in Fig. 1, the presence or absence of the next candidate to which the signal value should be propagated is checked. If there is a next candidate, the process of step 13 is performed again. If there is no next candidate, the process of examining the propagation status of the signal value is performed. Move (step 14). In order to help understand the repetitive process from step 14 to step 13 and from step 13 to step 14, we will explain how signal values propagate through the circuit in Figure 2 and the state of the next candidate that appears as a result of signal value propagation. The steps are shown in Fig. 3 in sequence. Step 11 in Figure 3. This is the circuit after step 12 is completed, and only the external output 211 and the external output 212 are propagated with the signal value "'1". The next candidates at this time are component 209 and component 210. Next, step 13 is not performed due to the condition determination in step 14, so the circuit's
The condition is shown in Figure 3.

In FIG. 3, the signal value "'1" is propagated to the constituent elements 2oe and wltl unformed 210, which were the next candidates in FIG. 3a. At this point -, there is still another candidate for -, so the condition determination step 140 is executed, and the system processor 13 is executed, resulting in the state shown in FIG. 3O.

The states of the circuits shown in FIGS. 3C1 and 3D have undergone the same process as the states of the circuits shown in FIGS. 1 and 3. In FIG. 3d, there is no next candidate, so step 13. The repetition between steps 14 ends at this point. In FIG. 3d, component 2 has no output.
Since no signal value is propagated to 06, it is relatively easy to find a component with no output in the circuit.

Next, steps after step 16 in FIG. 1 will be explained.

In step 15, constituent elements corresponding to external inputs of the circuit are selected. In the circuit shown in FIG. 3d, external inputs 200. External human resources 201. External input 2o2. External input 2o3. External input 204 is selected.

Next, in step 16 of FIG. 1, it is determined whether a signal value is being propagated to the selected component. As shown in FIG. 3d, since signal values have been propagated to all the external inputs selected in step 16, the process moves to step 17.

In step 17, the component connected to the output of the component selected in step 16 is added to the next candidates for signal value testing. In FIG. 3d, component 206° and component 2o6. without output. Component 207. Component 208. Component 2
0-9 are added to the next candidates for signal value testing. On the other hand, if the signal value is not propagated to the selected component in step 16 (the component 2 with no output in FIG. 3d)
If 06 is selected) remove this component from the circuit (step 19) and proceed to step 1B. In FIG. 3d, the components without outputs 06 to which no signal values are propagated are removed, resulting in the circuit shown in FIG. 4.

In step 18, it is checked whether there is a next candidate for signal value testing.

In step 18, if there is a next candidate for signal value test, step 16. Step 17° The process of step 18 is repeated. - If there is no next candidate for force signal testing, the process of removing components with no output from the circuit to be subjected to logic simulation ends.

By the method described above, components with no output are removed from the circuit that is the target of logic simulation, so more efficient logic simulation can be performed without unnecessary processing compared to the circuit before the components and children are removed. be able to.

However, even if by removing the component 409 with no output as in the circuit shown in FIG. 6, the component 406 connected to the component 409 with no output becomes a component with no output. The signal value propagation in this method is as shown in Figure 6, and since no signal is propagated to the component 406, when removing the component to which no signal value is propagated, the component 406 is first removed (on the output side). ) can be removed in -degrees (Fig. 6C). Furthermore, in the example, the signal value is propagated to all the constituent elements that affect the external output of the circuit, but in a circuit where these constituent elements/children are transistors (Figure 6a), the transistors connected to each other are By treating this group as one constituent element and changing the circuit in Figure 6a to the circuit in Figure 6A, the transistors in the group can be Since there is no need to propagate or test signal values, the process of removing non-output components from the circuit to be subjected to logic simulation can be performed at high speed.

Effects of the Invention As explained above, according to the present specification, the logical simulation
unnecessary processing by propagating a signal from the output side to the input side of the circuit that is the subject of the It is possible to perform efficient logic simulations without performing any additional steps, and is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of an embodiment of the logic simulation method of the present invention, FIG. 2, and FIG. t53. FIGS. 4, 6, and 6 are circuit diagrams for specifically explaining the logic miniaturization method of the same embodiment. 11...Select the component corresponding to the external output of the circuit, 12...Propagate any signal value to the selected component, 16...Selected configuration A signal is being propagated to the element, 19...The selected component is removed from the circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3〃≦Must0J)I, sum 2,403,404- External input Figure 5 11J2.473 =-External output 4Uζ soo, 5ot--One person power

Claims (1)

[Claims] As a target of logic simulation, an arbitrary signal is propagated from the output side of a circuit stored in the memory of a computer toward the input side of the circuit, and whether or not the signal propagates from the input side to the output side of the circuit is determined. By scanning while examining the circuit, a component having no output is found among the components of the circuit, and after removing the component,
A logic simulation method for performing a logic simulation targeting the circuit.